OVERVIEW A23187 is a carboxylic acid antibiotic which simultaneously uncouples oxidative phosphorylation and inhibits ATPase of rat liver mitochondria incubated in a magnesium-free medium. The antibiotic acts as a freely mobile carrier to transport calcium and magnesium, but not potassium, from an aqueous medium buffered at pH 7.4 into a bulk organic phase. A23187 causes a progressive release of endogenous...